Conventional communication systems often include one or more call servers, which are used to establish and support communication sessions in the systems. For example, a typical call server could receive requests to initiate telephone calls or conference calls. The server then establishes one or more connections or channels used to transport audio or video information during the calls. A problem with conventional call servers is that they typically need to determine whether to accept further communication sessions in order to prevent overloading. It is often difficult for conventional call servers to determine whether to accept further communication sessions during different operating conditions, such as when a rapid series of short communication sessions are established.